This invention refers to horizontal rolling piston rotary compressor and, particularly, to a new construction of a housing for this type of compressor used in refrigerators, freezers and other refrigeration appliances. The adequate amount of oil inside a compressor is an important factor for its good operation, as the good lubrication of movable parts and the cooling of the electric motor depend on this.
Another important function of oil is its capacity to absorb the refrigerant gas from the cooling system.
Such absorption causes, at compressor stops, the lowering of equalized pressures in suction and discharge of the compressor. Thus, the larger the amounts of oil inside the compressor housing, the larger will be the amount of absorbed refrigerant fluid and, consequently, the lower the equalized pressure and easier the start of the compressor after each stop, i.e, the compressor will start with lower voltages, improving its power performance.
In horizontal rolling piston rotary compressors, the maximum oil level inside the housing is limited, on the one hand, by the outside diameter of the motor rotor, which has to rotate freely without skidding on the oil film. On the other hand, the amount of oil is limited by the inside diameter of the compressor housing.
The rolling piston rotary compressors do not need the suspension system of the cylinder/motor unit by springs, since their vibration level is low (almost perfect balancing). Due to this fact, these compressors may have the cylinder/electric motor unit rigidly fastened to the housing. Thus, the manufacturers choose substantially circular housings of round transversal section, which are easy to manufacture.
The above mentioned restrictive aspects, bring about a reduction of the quantity of oil to be used for the compressor, limiting all benefits which a larger amount of oil could offer.
It is known that horizontal rotary compressors must operate with a quantity of oil equivalent to the similar vertical models. However, due to the already described restrictions, these compressors operate with a lesser quantity of oil.
One of the possibilities which could be used to increase the oil level in horizontal compressors would be to diminish the diameter of the electric motor rotor, which, obviously, is undesirable, as it would reduce the efficiency of the motor and also cause difficulty in the standardization between the horizontal and vertical models of the same series.
Another possibility to increase the quantity of available oil would be simply to increase the length of the housing and, consequently, its inside volume, which is, obviously, a disadvantage, as it would raise the expenses for raw material and require a larger space to be occupied by the compressor when assembled in, the refrigerator.